Dry material mixing apparatus



June 13, 1961 E. A. MEVISSEN 2,988,339

DRY MATERIAL MIXING APPARATUS Filed Feb. 6, 1958 FIG- 1 M1 II:\ /9 28 I nl L20 25/ W 22 23 ERNST A.MEV|SSEN BY i'M -rM United States Patent 2,988,339 DRY MATERIAL MIXING APPARATUS Ernst A. Mevissen, Coraopolis, Pa., assignor to Dravo Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Feb. 6, 1958, Ser. No. 713,724 Claims. (Cl. 259-57) This invention relates to the mixing of dry materials and is for an apparatus for mixing dry particles, granular materials or powdered materials or combinations of granular and powdered materials or the like.

In many industrial operations, dry materials must be thoroughly mixed together with an even distribution of one ingredient through another, or sometimes several ingredients must be simultaneously and uniformly mixed.

The present invention has for its principal object to provide a mixing apparatus for this purpose which may be made in a wide range of sizes, depending upon the amount of material to be processed, and which will thoroughly and effectively mix materials which are to be blended together. A further important object of this invention is to provide an apparatus in which the material will be agitated and mixed through a long distance of travel, but which apparatus is compact and requires relatively small floor space for the extent of agitation secured, and which may operate continuously, as distinguished from batch operation.

A further object of this invention is to provide one or more spiral paths designed to agitate the material as it is conveyed from one end of the spiral toward the other. These and other objects and advantages are obtained by my invention which may be fully understood by reference to the accompanying drawings, in which:

FIG. 1 is a side elevation of a simple form of apparatus embodying my invention;

FIG. 2 is a top plan view of one of the spiral conveyor units;

FIG. 3 is a top plan view of a complemental spiral conveyor unit; and

FIG. 4 discloses a modification showing the shaft vertical and showing the spirals relatively movable to the plates directly beneath them.

Referring first to FIGS. 1, 2 and 3 of the drawings, 2 designates a shaft having means such as gearing 3 for rotating it. It is supported in bearings 4 which hold it in an inclined position. On the shaft are a plurality of units alternately designated 5 and 6. Each unit 5 includes a supporting disk 7 having thereon a spiral strip or wall 8, the convolutions of which are separated to form a spiral channel 9 terminating at its inner end near the center of the disk, and terminating at its outer end at an opening through the disk. While the plate or disk 7 is inclined from a horizontal position, the inclination is such that material discharged into the spiral channel will be rotated in the channel and carried by rotation of the unit to the opposite end of the spiral channel and to the discharge opening at said end. Below this opening is a discharge spout 11. Each of the units 6 is similarly constructed with a disk 7a similar to the disk 7, and a spiral wall or flange 8a forming a spiral channel 9a. The spiral of the member 8a, however, is reversed with respect to the spiral of the member 5 and it has the outer convolution at 12. There is an opening 13 at the inner terminal of the spiral adjacent the shaft. There is a spout 14 under this discharge opening 13.

designates a chute through which dry ingredients are discharged from a source of supply onto the mixing device, the chute terminating close to the shaft 2 above the first unit 5 so that material is discharged into the center of the first unit. As the shaft 2 rotates, the

2,988,339 Patented June 13, 1961 material is carried along the channel 9 to the outer end of the spiral where it passes through the opening 10 and is discharged through the spout 11 into the outer convolution of the channel 9a of the unit 6. Because the pitch of the spiral of the unit 6 is reversed with respect to that of the unit 5, the material is carried by rotation of the disk toward the center, eventually passing out the opening 13 and the spout 14 of the second disk.

Because of the inclination of the shaft 2 and the movement of the material along the channels of the units 5 and 6, the materials to be mixed are agitated and rolled about in various directions until there is a uniform dis tribution of one through the other, and any initial stratification which may be present when the materials are discharged into the first unit is completely destroyed.

The number of units 5 and 6 will depend on the materials being treated, the diameter of the units, and the extent of mixing required. In some instances a single unit 5 may be sufficient; in others two units 5 and 6 will be adequate. In FIG. 1 I have shown four units, two of which are designated 5, and two of which are designated 6. The spout 14 on the lowermost unit discharges into a receiving trough 16 that surrounds the shaft 2, and which carries the mixed material to a place of discharge.

In the arrangement shown in FIG. 4 the spiral and plate are relatively movable. Here there is shown a shaft 17 which is vertical, and which has driving means 18 at its lower end, and which is carried in bearings 19 in a supporting frame (not shown). There are again a plurality of units alternately designated 20 and 21. Each unit 20 in this case comprises a bottom plate or disk 22 which is fixed on a support 23 and is restrained against rotation. Above it is a spiral strip 24 similar to the strip 8 of FIG. 1, which is attached to the shaft 17 so as to rotate with the shaft while the plate 22 is stationary. Each unit 21 has a similar spiral strip 24a thereon, the direction of which is reversed with respect to that of the unit 24, and the supporting plate 22a is stationary.

The plate 22 has a discharge opening therein near its periphery from which extends a spout 25 through which material is discharged into the outer portion of the unit 21 below it. The plate 22a of the unit 21 has a spout 26 near the center of the disk so that the material may discharge through the spout 26 to the center of the succeeding unit 20, or in the case of the last unit 21, into a receiving trough 27 which is similar to the receiving trough 16.

In this case the spirals rotate relatively to the plates on which they are carried. The material is caused to travel by the rotation of the spirals throughout the full length of the channel defined by the spiral walls, and is then discharged. This travel of the material agitates and churns the material which is delivered to the first unit through the delivery chute 28 so that the material is thoroughly agitated and mixed. Here again the number of units depends on the same factors as in the construction shown in FIG. 1. While the shaft in FIG. 4 has been shown as being vertical, it could be inclined as shown in FIG. 1, and the inclination of the shaft in either FIGS. 1 or 4 can be predetermined to secure the best results.

In either device the discharge of the material from one unit to the next, or into the discharge trough, is more or less intermittent, because with. the construction shown in FIG. 1 when the spout 11 is in the high position of the second unit 5 of FIG. 1, the material will gravitate away from the spout as it will in the high position of the spout 14 in the first unit 6. The piling up of the material and discharging it in this fashion also facilitates the mixing. In the arrangement shown in FIG. 4 there is a similar intermittent discharge since the spirals will alternately cover and uncover the opening of the discharge spout .25. Even though the spiral is level in the case shown in FIG. 4, there are combined radial and longitudinal components of motion to agitate the particles.

It will be seen that this device may be used in the continuous processing of material, since the materials to be mixed may be continuously delivered to the mixer at one end and continuously discharged from the other. Because of its compact construction, it may therefore be used in place of batch mixers presently available.

I have shown two specific embodiments of my invention, but it will be understood that this is by way of illustration and that various changes and modifications may be made therein within the comtemplation of my invention and under the scope of the following claims.

I claim:

1. Apparatus for mixing particulate material comprising a unit having a supporting plate member on which material may be retained, a spiral wall member on the upper face of the plate defining a spiral channel, means for delivering material to be mixed vertically onto the plate directly into one end of the spiral channel, there being a discharge opening through the plate at the other end of the spiral channel, at least one of said members being rotatable about the center of the spiral to eflFect transfer of the material along the spiral toward the discharge opening, and a second similar unit under the first having a supporting plate member and a similar spiral wall member and positioned so that material falling through the discharge opening of the first supporting plate member enters one end of the spiral channel of the second, and in which there is a discharge opening in the second supporting member at the opposite end of the spiral channel from the first, the spirals of the first and second units being effectively reversed so that one carries material from the center toward the periphery and the other from the periphery toward the center.

2. Material mixing apparatus comprising a plurality of spiral conveying units arranged in superimposed relation to one another along a common axis of rotation, means for rotating all of the units about the axis of rotation in the same direction, each unit having a discharge opening positioned to discharge material onto the one beneath, said openings being alternated one at the peripheral end of the spiral and the other at the center end, alternate spiral conveyors being effectively reversed to convey material toward its respective discharge opening.

3. Material mixing apparatus as defined in claim 2 in which the axis of rotation is inclined from a vertical and horizontal position, but sufiiciently vertical so that the conveying units are sufficiently close to a horizontal plane to retain material in the spiral conveyors.

4. Material mixing apparatus as defined in claim 2 in which said units are carried on a common drive shaft through which the rotation of all of the units about a common axis is effected.

5. Material mixing apparatus as defined in claim 2 in which said units are carried on a common drive shaft inclined from a vertical and horizontal position through which the rotation of all of the units about a common axis is effected, the spirals of the alternate conveyor units being reversed to progress the material in opposite directions in successive units while they rotate in the same direction.

References Cited in the file of this patent UNITED STATES PATENTS 481,532 Smith Aug. 23, 1892 579,679 Holmes Mar. 30, 1897 750,281 Hicks Jan. 26, 1904 953,961 Lancaster Apr. 5, 1910 1,081,421 Arnold Dec. 16, 1913 FOREIGN PATENTS 174,371 Austria Mar. 25, 1953 

